1. Field of the Invention
The present invention relates to a quantitative measuring method of argon impurity contained in high purity oxygen and cryostat employed in the above method and more particularly, to a quantitative measuring method of argon impurity by means of a triple point and a temperature at .gamma.-.beta. phase transition of the high purity oxygen and cryostat employed in the above method.
2. Description of the Prior Art
Generally, a purity of the high purity oxygen is determined by quantitative analysis of impurity using chemical analysis method. Currently, the high purity oxygen having the purity of 99.998% is commonly used.
The conventional chemical analysis method is usually performed by a mass measurement method using gas mass apparatus. And in this case, the chemical analysis apparatus using mass difference of an ionized gas, etc. measures a content of the impurity accurately.
However, because oxygen and argon have similar chemical properties (polarity, etc.), the signals of both gases are overlapped in case of using the conventional analysis method. Hence, the conventional analysis has a decisive shortcoming that a content of argon impurity is not accurately measured. Accordingly, it is required to provide a more accurate measurement method of argon impurity contained in high purity oxygen. And for the purpose of measuring argon impurity accurately, the signal of oxygen should be separated from that of argon.